Handle case when Redis cache returns an empty setting

lib/gitlab/current_settings.rb

@@ -11,7 +11,7 @@ module Gitlab
     def ensure_application_settings!
       if connect_to_db?
         begin
-          settings = ::ApplicationSetting.cached
+          settings = ::ApplicationSetting.current
         # In case Redis isn't running or the Redis UNIX socket file is not available
         rescue ::Redis::BaseError, ::Errno::ENOENT
           settings = ::ApplicationSetting.last

spec/lib/gitlab/current_settings_spec.rb

@@ -4,7 +4,7 @@ describe Gitlab::CurrentSettings do
   describe '#current_application_settings' do
     it 'attempts to use cached values first' do
       allow_any_instance_of(Gitlab::CurrentSettings).to receive(:connect_to_db?).and_return(true)
-      expect(ApplicationSetting).to receive(:cached).and_call_original
+      expect(ApplicationSetting).to receive(:current).and_return(::ApplicationSetting.create_from_defaults)
       expect(ApplicationSetting).not_to receive(:last)
 
       expect(current_application_settings).to be_a(ApplicationSetting)
@@ -18,9 +18,16 @@ describe Gitlab::CurrentSettings do
       expect(current_application_settings).to eq fake_application_settings
     end
 
+    it 'falls back to DB if Redis returns an empty value' do
+      allow_any_instance_of(Gitlab::CurrentSettings).to receive(:connect_to_db?).and_return(true)
+      expect(ApplicationSetting).to receive(:last).and_call_original
+
+      expect(current_application_settings).to be_a(ApplicationSetting)
+    end
+
     it 'falls back to DB if Redis fails' do
       allow_any_instance_of(Gitlab::CurrentSettings).to receive(:connect_to_db?).and_return(true)
-      expect(ApplicationSetting).to receive(:cached).and_raise(::Redis::BaseError)
+      expect(ApplicationSetting).to receive(:current).and_raise(::Redis::BaseError)
       expect(ApplicationSetting).to receive(:last).and_call_original
 
       expect(current_application_settings).to be_a(ApplicationSetting)